On the same computer that didn't work with 1.5, I get the error "GL_ARB_texture_rectangle must be supported" while running CheckRequirements(). I also get a Null Reference Exception at Project.tvl.WriteLine which presumably is just for writing the debug log or something. For what I do have in the debug log, see below.
I removed the throwing of the exception and recompiled, and was able to view the menu map. I had to disable audio because I couldn't figure out how to use the .bin files to embed the audio into the exe (this was not on a computer with a C# IDE), so it errored out on the fmod call, but the program did run and display the menu map, and then worked the same way I saw it on my other computer, running at about 500 FPS on Level 1. I didn't know how to compile in debug mode, so I can't tell you the exact number, but it was far too fast to be playable.
In any case, GL_ARB_texture_rectangle does not appear to be a requirement. At least, it did not show up in this project. This may be due to the fact that all of the graphic sheets are a power-of-two size.
DisplayDevice 0 (primary) supports 41 resolutions.
320x200x8@60Hz
320x200x16@60Hz
320x200x32@60Hz
320x240x8@60Hz
320x240x16@60Hz
320x240x32@60Hz
400x300x8@60Hz
400x300x16@60Hz
400x300x32@60Hz
512x384x8@60Hz
512x384x16@60Hz
512x384x32@60Hz
640x350x8@60Hz
640x350x16@60Hz
640x350x32@60Hz
640x400x8@60Hz
640x400x16@60Hz
640x400x32@60Hz
640x480x8@60Hz
640x480x16@60Hz
640x480x32@60Hz
720x480x8@60Hz
720x480x16@60Hz
720x480x32@60Hz
720x576x8@60Hz
720x576x16@60Hz
720x576x32@60Hz
800x600x8@60Hz
800x600x16@60Hz
800x600x32@60Hz
848x480x8@60Hz
848x480x16@60Hz
848x480x32@60Hz
1024x768x8@60Hz
1024x768x16@60Hz
1024x768x32@60Hz
1280x800x8@60Hz
1280x800x16@60Hz
>> 1280x800x32@60Hz <<
640x480x4@1Hz
800x600x4@1Hz
Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Device context: 503385581
Selecting pixel format... Creating GraphicsContext.
GraphicsMode: Index: 3, Color: 32 (8888), Depth: 24, Stencil: False, Samples: 0, Accum: 0 (0000), Buffers: 2, Stereo: False
IWindowInfo: Windows.WindowInfo: Handle 263484, Parent (null)
Loaded opengl32.dll: 1590689792
OpenGL will be bound to handle: 263484
Setting pixel format...
3
Creating render context... done! (id: 65536)
Load extensions for OpenTK.Platform.Windows.Wgl... 43 extensions loaded in 79 ms.
Load extensions for OpenTK.Graphics.OpenGL.GL... 913 extensions loaded in 629 ms.
Load extensions for OpenTK.Graphics.OpenGL.Glu... 58 extensions loaded in 16 ms.
Extension "
1.3.3842 WinXP Release
gl_arb_multitexture
gl_arb_point_parameters
gl_arb_texture_border_clamp
gl_arb_texture_compression
gl_arb_texture_cube_map
gl_arb_texture_env_add
gl_arb_texture_env_combine
gl_arb_texture_env_crossbar
gl_arb_texture_env_dot3
gl_arb_texture_mirrored_repeat
gl_arb_transpose_matrix
gl_arb_vertex_blend
gl_arb_vertex_buffer_object
gl_arb_vertex_program
gl_arb_window_pos
gl_ati_element_array
gl_ati_envmap_bumpmap
gl_ati_fragment_shader
gl_ati_map_object_buffer
gl_ati_texture_env_combine3
gl_ati_texture_mirror_once
gl_ati_vertex_array_object
gl_ati_vertex_attrib_array_object
gl_ati_vertex_streams
gl_atix_texture_env_combine3
gl_atix_texture_env_route
gl_atix_vertex_shader_output_point_size
gl_ext_abgr
gl_ext_bgra
gl_ext_blend_color
gl_ext_blend_func_separate
gl_ext_blend_minmax
gl_ext_blend_subtract
gl_ext_clip_volume_hint
gl_ext_compiled_vertex_array
gl_ext_draw_range_elements
gl_ext_fog_coord
gl_ext_multi_draw_arrays
gl_ext_packed_pixels
gl_ext_point_parameters
gl_ext_rescale_normal
gl_ext_secondary_color
gl_ext_separate_specular_color
gl_ext_stencil_wrap
gl_ext_texgen_reflection
gl_ext_texture_compression_s3tc
gl_ext_texture_cube_map
gl_ext_texture_edge_clamp
gl_ext_texture_env_add
gl_ext_texture_env_combine
gl_ext_texture_env_dot3
gl_ext_texture_filter_anisotropic
gl_ext_texture_lod_bias
gl_ext_texture_object
gl_ext_texture_rectangle
gl_ext_texture3d
gl_ext_vertex_array
gl_ext_vertex_shader
gl_hp_occlusion_test
gl_nv_blend_square
gl_nv_occlusion_query
gl_nv_texgen_reflection
gl_s3_s3tc
gl_sgi_color_matrix
gl_sgis_generate_mipmap
gl_sgis_multitexture
gl_sgis_texture_border_clamp
gl_sgis_texture_edge_clamp
gl_sgis_texture_lod
gl_sun_multi_draw_arrays
gl_version_1_1
gl_version_1_2
gl_version_1_3
gl_win_swap_hint
wgl_ext_extensions_string
wgl_ext_swap_control